Such mats are known, and they are widely used, especially as indoor or outdoor floor mats at the entrance of public or office buildings. Depending on the type of tread members to be inserted into the rails, the mats are suitable for removing coarse or fine dirt from shoes upon entering the building and/or for providing a scraping effect as well as drainage of water or melted snow. Each rail comprises a receiving portion having on both sides longitudinally upstanding edge portions with horizontal top flanges which retain and thus fix a tread member in the rail after this has been inserted into the receiving portion of the rail.
In many cases, when assembling a mat with the aid of the coupling means having the shape of longitudinally extending grooves and corresponding ribs, both being integrated with the rails, successive rails are joined by sliding them endwise. The tread members are to be inserted into the receiving portion along the rail towards the other end, which operation is usually carried out in an assembling apparatus.
European Patent Application 0125618 discloses a mat of the preamble of claim 1, including rails that are connected by separate gutter-shaped connectors which are snapped into the rails. Tread members are accomodated in tread-member-receiving rails which are provided with snap connection means for being connected to the rails by downward insertion into the rails. Therefore, the assemblage of the known mat requires a considerable number of actions to be performed, i.e. the connection of the tread members to the tread-member-receiving rails, the connection of the latter rails to the supporting rails, and the interconnection of the supporting rails.